Micro LED display panel and method of manufacturing same

ABSTRACT

A micro LED display panel according to the present disclosure includes a substrate including a light emitting region and a driving region; a micro LED arranged in the light emitting region on the substrate, a transistor element arranged in the driving region on the substrate and driving the micro LED, a first connection wiring electrically connecting the micro LED and the transistor, and a color adjustment layer arranged in the light emitting region under the substrate. The micro LED display panel according to the present invention can form the micro LED and the transistor element for driving the micro LED on a growth substrate such as a sapphire substrate together on the same plane so that the micro LED does not require a transfer process, and it is possible to manufacture polysilicon when manufacturing the micro LED, and can simplify the process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of Republic of KoreaPatent Application No. 10-2017-0177835, filed on Dec. 22, 2017, thedisclosure of which is incorporated herein by reference in its entirety.

BACKGROUND 1. Field of the Invention

The present disclosure relates to a display panel, and moreparticularly, to a micro LED display panel.

The present disclosure also relates to a method of manufacturing a microLED display panel.

2. Description of Related Art

Recently, the most widely developed display devices include a LiquidCrystal Display (LCD), an Organic Light Emitting Diode (OLED) display,and a Quantum dot Light Emitting Diode (QLED) display, etc.

In the case of the liquid crystal display device from among these, thereis no self-light emitting means in the display panel. Accordingly, inthe case of the LCD device, a separate backlight for supplying light tothe display panel has to be provided, and a nitride-based LED has beenmainly used as a light source.

On the other hand, in the case of the OLED display and the QLED display,they have the OLED and the QLED that emit light themselves, so that noseparate backlight is required, and a response speed is high, and alight emitting efficiency, a brightness, and viewing angle are large.However, the QLED and the OLED require encapsulation technology toprevent a penetration of moisture, air, etc.

A micro LED generally means an LED having a size of one side of 100 μmor less. This corresponds to about 1/10 or less size compared to thegeneral LEDs. These micro LEDs are known to have an energy efficiency ashigh as about 20% or more than the general LEDs, have a small heatgeneration rate due to their small size, and have a small powerconsumption. Due to these advantages, many studies have been made toapply the micro LEDs to the display devices.

However, the micro LED have not yet been applied to the display becauseit lacks technology to transfer a chip on which the micro LED is formedto each pixel of the display panel.

In a process of transferring the chip on which the micro LED is formedto each pixel of the display panel, an accuracy is closely related to adefect occurrence rate of the display panel. Also, the speed of atransfer process is related to a production cost reduction. Accordingly,studies are actively proceeded to improve the transfer process speed forshortening the production cost while accurately transferring the chip onwhich the micro LED is formed to each pixel of the display panel.

In addition, research has been conducted on a method of forming a pixelof the display panel without transferring a chip on which the micro LEDis formed to a display panel. A transistor element can be formed on themicro LED in order to form the micro LED and drive the micro LED. Sincea contact hole having a high aspect ratio has to be formed in order toconnect the transistor element and the micro LED, a high processaccuracy is required, and a thickness of an entire display device isincreased since it is a stacked structure.

SUMMARY OF THE INVENTION

It is an object of the present disclosure to provide a micro LED displaypanel in which a micro LED and a transistor element for driving themicro LED are arranged on the same plane.

In addition, it is another object of the present disclosure to provide amethod of manufacturing a micro LED display panel without transferring achip on which the micro LED is formed.

The micro LED display panel according to the embodiments of the presentinvention for overcoming the above problem includes a substrate, a microLED, a transistor element, a first connection wiring, and a coloradjustment layer.

The substrate includes a light emitting region and a driving region. Themicro LED is arranged in the light emitting region on the substrate. Thetransistor element is arranged in the driving region on the substrateand drives the micro LED. The first connection wiring electricallyconnects the transistor element and the micro LED so that the transistorelement can drive the micro LED. The color adjustment layer is arrangedin the light emitting region under the substrate.

According to the above configuration, the micro LED and the transistorelement for driving the micro LED are arranged on the same plane.Accordingly, the thickness of the micro LED display panel can bethinned, and a contact hole having a relatively low aspect ratio can beformed as compared to a stacked structure, so that a connection betweenthe micro LED and the transistor element for driving the micro LED iseasy.

The substrate may be a sapphire substrate, and the micro LED may be anitride-based micro LED, and the transistor device may be a polysiliconthin film transistor device. The nitride-based micro LED can be formedon a sapphire growth substrate by a MOCVD process at about 900° C. toabout 1300° C., and the temperature is high enough to convert anamorphous silicon into polysilicon. Accordingly, polysilicon can bemanufactured without a separate laser process, and a polysilicon thinfilm transistor can be manufactured on the sapphire substrate based onthe above.

Specifically, the first connection wiring may be a wiring forelectrically connecting a p-type semiconductor layer of the micro LEDand a drain electrode of the transistor element. In addition, a secondconnection wiring for connecting a n-type semiconductor layer of themicro LED with a voltage source to source line (VSS) may be furtherincluded. The voltage source to source line may be arranged on thesubstrate. As another example, the voltage source to source line may bearranged on a substrate for a display device such as a glass substrateon which the micro LED display panel according to the present inventionis mounted.

In addition, a protection layer arranged on the transistor element andthe micro LED can be further included. The first connection wiring canbe arranged through the contact hole penetrating through the protectionlayer. Thus, a wire bonding process for connecting the micro LED and thetransistor element for driving the micro LED can be omitted. On theother hand, the second connection wiring can be also arranged throughthe contact hole penetrating through the protection layer.

In addition, the color adjustment layer may include a color conversionfilm and/or a color filter including at least one of a quantum dot and afluorescent material. Through this color adjustment layer, a RGB fullcolor can be realized.

In addition, a bank layer arranged in a region except the light emittingregion under the substrate can be further included. By forming the banklayer in an region other than the light emitting region, a light leakagepreventing effect can be obtained.

A method for manufacturing a micro LED display panel according to theembodiments of the present invention for overcoming the above problemsincludes: arranging an amorphous silicon layer and a temporaryprotection layer in a driving region on a substrate including a lightemitting region and the driving region; arranging an n-typesemiconductor layer, an active layer and a p-type semiconductor layer onthe substrate on which the amorphous silicon layer and the temporaryprotection layer are arranged, and converting the amorphous siliconlayer into a polysilicon layer; removing the n-type semiconductor layer,the active layer, and the p-type semiconductor layer in a remainingregion except the light emitting region to manufacture a micro LED;removing the temporary protection layer, and then manufacturing thetransistor element on the polysilicon layer; and arranging a coloradjustment layer in the light emitting region under the substrate.

The method can further include, after manufacturing the transistorelement, forming a first connection wiring for electrically connectingthe p-type semiconductor layer of the micro LED to a drain electrode ofthe transistor element; and forming a second connection wiring forelectrically connecting the n-type semiconductor layer of the micro LEDto a voltage source to source line (VSS). The first connection wiringand the second connection wiring may be formed sequentially andsimultaneously.

Through these processes, the micro LED and the transistor element fordriving the micro LED can be formed on the same plane on the substrate,and in particular, the micro LED display panel can be manufacturedwithout transferring the micro LED.

The substrate may be a sapphire substrate, and the micro LED may be anitride-based micro LED. A nitride semiconductor represented by GaN canbe epitaxially grown on the sapphire substrate with an excellent crystalquality.

In addition, the n-type semiconductor layer, the active layer, and thep-type semiconductor layer are formed by the MOCVD process, and theamorphous silicon layer may be converted into polysilicon by heat duringthe process of forming the n-type semiconductor layer, the active layer,and the p-type semiconductor layer. The MOCVD process for epitaxiallygrowing the nitride semiconductor is mainly performed at a hightemperature of about 900° C. to about 1300° C., and the temperaturecorresponds to a temperature sufficient to convert the amorphous siliconinto a crystalline silicon. Accordingly, when the MOCVD process isperformed at a high temperature in a state in which the amorphoussilicon layer is arranged, it can be converted into the crystallinesilicon without a separate heat treatment or laser irradiation withregard to the amorphous silicon layer.

In addition, the method may further include arranging the protectionlayer on the substrate on which the transistor element and the micro LEDare disposed. The first connection wiring and the second connectionwiring may be formed through contact holes penetrating through theprotection layer. The first connection wiring and the second connectionwiring can be arranged on different planes or can be arranged on thesame plane.

Through a wiring connection using the protection layer, the micro LEDcan be easily electrically connected to the transistor element and thevoltage source to source line without a separate wire bonding process.In addition, since the micro LEDs and the transistor element for drivingthe micro LED are arranged on the same plane on the substrate, theaspect ratio of the contact holes can be relatively low as compared withthe stacked structure.

In the case of the method of manufacturing a micro LED display panelaccording to the present invention, the micro LED and the transistorelement for driving the micro LED are formed on the same plane on thegrowth substrate such as the sapphire substrate, so that the micro LEDdoes not need to be transferred.

In addition, in the case of the micro LED display panel according to thepresent invention, the thickness of the panel can be thinned byarranging the micro LED and the transistor element for driving the microLED on the same plane.

Embodiments also relate to a micro light emitting diode (LED) displaypanel. The micro LED display panel includes a substrate having a lightemitting region and a driving region, a micro LED arranged in the lightemitting region on the substrate, a transistor element arranged in thedriving region on the substrate and drives the micro LED, a firstprotection layer covering the micro LED and the transistor element. Thefirst protection layer includes one or more first contact holes. Themicro LED display panel also includes a first connection wiringelectrically connecting the micro LED to the transistor element throughthe one or more first contact holes in the first protection layer.

Embodiments also relate to a method for manufacturing a micro lightemitting diode (LED) display panel. A transistor element is formed on asubstrate having a light emitting region and a driving region. Thetransistor element is arranged in the driving region of the substrate. Amicro LED is formed on the substrate. The micro LED is arranged in thelight emitting region of the substrate. A first protection layer isformed on the transistor element and on the micro LED. The firstprotection layer includes one or more first contact holes. A firstconnection wiring electrically connects the micro LED to the transistorelement through the one or more first contact holes.

Embodiments also relate to a micro light emitting diode (LED) displaypanel. The micro LED display panel includes a substrate having a lightemitting region and a driving region, a micro LED arranged in the lightemitting region on the substrate, a transistor element arranged in thedriving region on the substrate that drives the micro LED. Thetransistor element is disposed horizontally adjacent to the micro LED onthe substrate. The micro LED display panel also includes a protectionlayer covering the micro LED and the transistor element, and a firstconnection wiring electrically connecting the micro LED to thetransistor element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a micro LED display panelin accordance with an exemplary embodiment of the present disclosure.

FIG. 2 shows an example of a cross-sectional structure of a micro LED inaccordance with an embodiment of the present disclosure.

FIG. 3 shows an example of a cross-sectional structure of a transistorelement in accordance with an embodiment of the present disclosure.

FIG. 4 shows a schematic plan view of a display device including a microLED display panel in accordance with an exemplary embodiment of thepresent disclosure.

FIG. 5 shows an example of a cross-sectional structure taken along lineI-I′ of FIG. 4 in accordance with an embodiment of the presentdisclosure.

FIGS. 6A to 6G show a method of manufacturing a micro LED display panelin accordance with an exemplary embodiment of the present disclosure.

FIG. 7 is a schematic cross-sectional view of a micro LED display panelin accordance with an exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, an embodiment of a micro LED display panel according to thepresent invention will be described with reference to the drawings.

The terms including the ordinal numbers such as a first, a second, etc.in the following can be used to describe various components, but thecorresponding components are not limited by such terms. These terms areused only to distinguish one component from another.

Also, in the present invention, the expression “is on˜” means not only“it is immediately on the other part in a state in which any part is incontact with the other part” but also “it is on the other part in astate in which any part is in non-contact with the other part or thethird part is further formed in the middle”.

FIG. 1 is a schematic cross-sectional view of a micro LED display panelin accordance with an exemplary embodiment of the present disclosure.

Referring to FIG. 1, the micro LED display panel 100 according to thepresent disclosure includes a substrate 110, a micro LED 120, atransistor element 130, a first connection wiring 140 a, and a coloradjustment layer 160.

The substrate 110 may include a light emitting region and a drivingregion. In FIG. 1, the region in which the micro LED 120 is arranged maybe the light emitting region, and the region in which the transistorelement 130 is arranged may be the driving region.

The substrate 110 is a sapphire substrate, and the micro LED 120 is anitride-based micro LED, and the transistor element 130 may be apolysilicon thin film transistor element, but is not limited thereto.The substrate 110, the micro LED 120, and the transistor element 130 canbe changed depending on the structures and properties of the micro LED120 and the transistor element 130. For example, the transistor element130 may be an oxide thin film transistor element.

Also, the substrate 110 may be gallium nitride (GaN) substrate for anitride-based micro LED. However, a single crystal substrate 110 usingGaN is difficult to manufacture and has a disadvantage of high unitcost. Accordingly, the substrate 110 can be applied with sapphire, or Si(silicon), SiC (silicon carbide), GaAs (gallium arsenide), and ZnO (zincoxide), which are relatively easy to obtain and have a low unit cost. Asapphire substrate capable of forming a high quality nitridesemiconductor with a relatively small difference in lattice constantfrom the nitride semiconductor is more preferable.

Amorphous silicon can be converted into polysilicon in the process ofmanufacturing nitride-based micro LEDs on the sapphire substrate.

The micro LED 120 may be arranged in the light emitting region on thesubstrate 110. FIG. 2 shows an example of a cross-sectional structure ofthe micro LED 120.

The micro LED 120 may include an n-type semiconductor layer 121, anactive layer 122, and a p-type semiconductor layer 123. In the activelayer 122, the electrons supplied from the n-type semiconductor layer121 and the holes supplied from the p-type semiconductor layer 123 arerecombined to generate light. As shown in FIG. 2, the micro LED 120 mayhave a structure in which at least a part of the n-type semiconductorlayer 121 extends horizontally beyond the p-type semiconductor layer123. The second connection wiring 140 b may contact the part of thep-type semiconductor layer 123. Of course, reference numeral 121 may bea p-type semiconductor layer, and reference numeral 123 may be an n-typesemiconductor layer. Hereinafter, it is explained by assuming thatreference numeral 121 is an n-type semiconductor layer and referencenumeral 123 is a p-type semiconductor layer.

The micro LED 120 may include a nitride-based semiconductor representedby GaN. For example, n-GaN as the n-type semiconductor layer 121,GaN/InGaN as the active layer 122, and p-GaN as the p-type semiconductorlayer 123 can be presented. In the case of the p-type conductive layer123, it has the relatively high resistance, a conductive layer 124 bbeing made of a metal such as Al, Cu, Cr, or Ni, a transparentconductive oxide (TCO) such as Indium Tin Oxide (ITO) or Fluorine-dopedTin Oxide (FTO), etc. can be further arranged for a current disperse ofthe p-type semiconductor layer 123. Another conductive layer 124 a maybe further arranged on the n-type semiconductor layer 121 as well.

Meanwhile, a buffer layer made of AlN, GaN, etc. may be further includedbetween the substrate 110 and the n-type semiconductor layer 121 toimprove a crystal quality. In addition, the micro LED 120 may includevarious known functional layers.

The transistor element 130 is arranged in the driving region on thesubstrate 110 and serves to drive the micro LED 120. The transistorelement 130 may be disposed horizontally adjacent to the micro LED 120on the substrate 110. At least a part of the transistor element 130 andat least a part of the micro LED 120 may contact the same substrate 110.FIG. 3 shows an example of the cross-sectional structure of thetransistor element 130 of FIG. 1 in accordance with an embodiment of thepresent disclosure.

Referring to FIG. 3, the transistor element 130 may include an activelayer 131 including a channel region, a source region, and a drainregion. The active layer 131 may be an amorphous silicon semiconductormaterial, a polysilicon semiconductor material, or an oxidesemiconductor material. The active layer 131 may form a channel betweena drain electrode 135 a and a source electrode 135 b. The transistorelement 130 may include a gate insulating layer 132 formed with thecontact hole on the active layer 131, a gate electrode 133 formed on thegate insulating layer 132, an inter layer dielectric 134 formed with thecontact hole on the gate electrode 133 and the gate insulating layer132, the drain electrode 135 a connected with the drain region of theactive layer 131 through the contact hole of the gate insulating layer132 and the inter layer dielectric 134, and the source electrode 135 bconnected to the source region of the active layer 131. Since thetransistor element 130 is disposed horizontally adjacent to the microLED 120, the transistor element 130 may not overlap with the micro LED120 in a vertical direction. For example, the active layer 131 may notoverlap with the micro LED 120 in a vertical direction that is adirection perpendicular to the substrate 110.

The first connection wiring 140 a may serve to electrically connect thep-type semiconductor layer 123 of the micro LED 120 and the drainelectrode 135 a of the transistor element 130. Meanwhile, the secondconnection wiring 140 b may be further included and the secondconnection wiring 140 b serves to connect the n-type semiconductor layer121 of the LED 120 and the voltage source to source line VSS (referringto FIG. 5).

In addition, a first protection layer 150 a may be further arranged onthe substrate 110 on which the micro LED 120 and the transistor element130 for driving the micro LED 120 are arranged. In addition, a secondprotection layer 150 b may be further arranged on the first protectionlayer 150 a. The first protection layer 150 a and the second protectionlayer 150 b may be formed of an organic material such as a Photo AcrylCompound (PAC), an inorganic material such as SiO₂ or SiN_(x), with asingle layer or a multilayer, and serve as an insulating layer and aplanarization layer.

Meanwhile, referring to FIG. 1, the first connection wiring 140 a may bearranged under the second protection layer 150 b in order to connect themicro LED 120 and the transistor element 130. In view of a processaspect, the first protection layer 150 a is arranged on the substrate110 and a contact hole penetrating through the first protection layer150 a is formed to connect the micro LED 120 and the transistor element130, and the first connection wiring 140 a may be arranged, and then thesecond protection layer 150 b may be arranged. The first protectionlayer 150 a may be formed with one or more first contact holes 152, 154to electrically connect the micro LED 120 and the thin film transistor.Specifically, the first connection wiring 140 a may electrically connectthe micro LED 120 to the thin film transistor through the one or morefirst contact holes formed in the first protection layer 150 a. Thefirst connection wiring 140 a may include a first part extendingvertically down to contact an exposed portion of the micro LED 120,specifically the p-type semiconductor layer 123, through a contact hole152, and a second part extending vertically down to contact an exposedportion of the transistor element 130, specifically the drain electrode,through another contact hole 154 in the first protection layer 150 a.

On the other hand, a part of the second connection wiring 140 b may bearranged on the second protection layer 150 b. The second connectionwiring 140 b may be arranged to connect the micro LED 120 and thevoltage source to source line VSS after forming the contact holepenetrating through the first protection layer 150 a and the secondprotection layer 150 b. Thus, the second connection wiring 140 b mayelectrically connect the micro LED 120 to the voltage source to sourceline VSS through one or more second contact holes 156 in the firstprotection layer 150 a and second protection layer 150 b. The voltagesource to source line VSS may extend in a direction parallel to thesubstrate 110.

The color adjustment layer 160 is arranged in a light emitting regionunder the substrate 110, and may include at least one of a colorconversion film and a color filter.

The color conversion film may include a color conversion material suchas a fluorescent material or a quantum dot. For example, when blue lightis emitted from the micro LED 120, a white light can be realized whenthe color adjustment layer 160 includes a color conversion material suchas a red fluorescent material and a green fluorescent material. Inaddition, when the white light is emitted from the LED 120, a blue colorfilter, a green color filter, and a red color filter may be arranged inthe color adjustment layer 160 for each light emitting region. Also, thered light, the green light, and the blue light can be independentlyemitted according to the light emitting region while the white lightpasses through the blue color filter, the green color filter, and thered color filter.

The micro LED display panel according to the present disclosure canrealize a RGB full color through the color adjustment layer 160.

Meanwhile, a bank layer 165 may be arranged in a region except the lightemitting region under the substrate 110. By forming the bank layer 165in a region other than the light emitting region, a light leakagepreventing effect can be obtained.

FIG. 4 shows a schematic plan structure of a display device including amicro LED display panel in accordance with an exemplary embodiment ofthe present disclosure, and FIG. 5 is a cross-sectional view taken alongline I-I′ of FIG. 4 in accordance with an embodiment of the presentdisclosure.

The example shown in FIG. 4 shows that the micro LED display panel 100according to the present disclosure is arranged on the substrate 201 forthe display device. In this case, the micro LED display panel 100 can beadhered in a module form to the substrate 201 for the display device inwhich the data line DL, the gate line GL, and the voltage source tosource line VSS are arranged.

However, the present disclosure is not limited thereto. For example, adata line DL, a gate line GL, and a voltage source to source line VSSmay be arranged on the substrate 110 for forming a micro LED and atransistor element. In this case, the data line DL, the gate line GL,the voltage source to source line VSS, the micro LED 120 and thetransistor element 130 are all arranged on the substrate 110 such as asapphire.

Referring to FIGS. 4 and 5, the data line DL, the gate line GL, and thevoltage source to source line VSS are arranged on the substrate 201 forthe display device. The source electrode 135 b is connected to the dataline DL. The gate electrode 133 is connected to the gate line GL. Thep-type semiconductor layer 123 of the micro LED is electricallyconnected to the drain electrode 135 a through the first connectionwiring 140 a. Also, the n-type semiconductor layer 121 of the micro LEDis connected to the voltage source to source line VSS via the secondconnection wiring 140 b.

In FIG. 5, the first connection wiring 140 a is arranged on the firstprotection layer 150 a through the contact hole penetrating through thefirst protection layer 150 a and the second connection wiring 140 b isarranged on the second protection layer 150 b through the contact holespenetrating through the first protection layer 150 a and/or the secondprotection layer 150 b. It is a structure that the first connectionwiring 140 a is first formed, and then, the second connection wiring 140b is formed.

However, the present disclosure is not limited thereto, and as theexamples shown in FIG. 7, each first connection wiring 140 a and secondconnection wiring 140 b are arranged on the first protection layer 150 athrough the contact hole penetrating through the first protection layer150 a. It can be seen as the structure that the first connection wiring140 a and the second connection wiring 140 b are formed at the sametime. Thus, both the first connection wiring 140 a and the secondconnection wiring 140 b may contact the first protection layer 150 a.

The connection wiring structure shown in FIG. 5 can be applied when thefirst connection wiring 140 a and the second connection wiring 140 b areoverlapped, and the connection wiring structure shown in FIG. 7 can beapplied when the first connection wiring 140 a and the second connectionwiring 140 b are not overlapped.

According to the micro LED display panel of the present disclosure, themicro LEDs 120 and the transistor elements 130 for driving the microLEDs 120 may be arranged on the same plane on the substrate 110. Themicro LED 120 and the transistor element 130 for driving the micro LED120 may be disposed horizontally adjacent to each other on the substrate110. Specifically, the micro LED 120 and the transistor element 130 maybe disposed to overlap in a direction parallel to the substrate 110.Accordingly, the thickness of the micro LED display panel can bethinned, and the contact holes having a relatively low aspect ratio canbe formed as compared with a stacked structure.

Hereinafter, a method of manufacturing the micro LED display panel shownin FIG. 4 will be described with reference to FIGS. 6A to 6G.

First, a substrate 110 is prepared as the example shown in FIG. 6A. Thesubstrate 110 may be the sapphire substrate. In the substrate 110, alight emitting region LA and a driving region DA are defined in advance.

Then, as the example shown in the FIG. 6B, an amorphous silicon layer112 is arranged in the driving region DA on the substrate 110, and atemporary protection layer 114 is arranged on the amorphous siliconlayer 112. The amorphous silicon layer 112 may be formed by patterningafter depositing amorphous silicon on the substrate. The temporaryprotection layer 114 serves as an etch stop layer in an etching processfor manufacturing a micro LED, which will be described later.

Then, as the example shown in FIG. 6C, an epitaxial growth process isperformed on the substrate 110 on which the amorphous silicon layer 112and the temporary protection layer 114 are arranged.

A n-type semiconductor layer 121, an active layer 122 and a p-typesemiconductor layer 123 can be formed through the epitaxial growthprocess. The n-type semiconductor layer 121, the active layer 122, andthe p-type semiconductor layer 123 may be formed of a nitridesemiconductor, respectively. The nitride semiconductor represented byGaN can be epitaxial grown on a sapphire substrate with the excellentcrystal quality.

The nitride-based LED may be formed by a metal organic chemical vapordeposition (MOCVD) process on the sapphire substrate, but is not limitedthereto. For example, it may be realized by a method such as MolecularBeam Epitaxy (MBE), Plasma Enhanced Chemical Vapor Deposition (PECVD)and Vapor Phase Epitaxy (VPE). The MOCVD process can be proceeded atabout 900° C. to about 1300° C.

Also, in this step, the amorphous silicon layer 112 can be convertedinto a polysilicon layer 131, that is, the active layer. It is possibleto heat the amorphous silicon layer 112 before the epitaxial growthprocess or after the epitaxial growth process to convert it into thepolysilicon layer 131 but preferably without a separate process ofconverting into the separate polysilicon layer 131, the amorphoussilicon layer 114 can be converted into the polysilicon layer 131 usinghigh temperature of about 900° C. to about 1300° C. applied to theepitaxial growth process. That is, the amorphous silicon can beconverted into polysilicon without a separate conversion process due tohigh temperature in the process for forming the LED.

Accordingly, it is possible to manufacture polysilicon in the process ofLED epitaxial growth, and it is possible to manufacture the polysiliconthin film transistor on a sapphire substrate based on the above. Forexample, as in the embodiments of the present disclosure, a hightemperature LED forming process is performed in a state in which theamorphous silicon layer is arranged on the sapphire substrate, theamorphous silicon can convert into polysilicon which is crystallinewithout a separate heat treatment process or laser irradiation process.

Meanwhile, as the example shown in FIG. 6C, a conductive layer 124 b maybe further arranged on the p-type semiconductor layer 123C. The p-typesemiconductor layer 123 has the relatively high resistance compared tothe n-type semiconductor layer 121 and a current uniformity can bedegraded. Thus, in order to improve the above, the conductive layer 124b can be formed with the metal or the transparent conductive oxide onthe p-type semiconductor layer 123. Of course, a conductive layer 124 acan be formed on the n-type semiconductor layer 121 as shown in theexample shown in FIG. 2.

Then, as the example shown in FIG. 6D, a micro LED can be manufacturedby removing the n-type semiconductor layer 121, the active layer 122,and the p-type semiconductor layer 123 in a remaining region except thelight emitting region. This can be performed by the etching processusing a mask. Further, in order to form the wirings, the additionaletching can be performed so as to expose a part of the n-typesemiconductor layer 121 in the etching process.

Then, as the example shown in FIG. 6E, a transistor element 130 can bemanufactured on the polysilicon layer 131, after removing the temporaryprotection layer 114. The structure and manufacturing method of thepolysilicon thin film transistor device are very diverse, but thefollowing process is presented as a representative example. Thetransistor element shown in FIG. 6E has substantially the same structureas that shown in FIG. 3, and thus, the description related to FIG. 3 canbe applied itself.

First, a gate insulating layer 132 is formed on the polysilicon layer131. Then, a gate electrode 133 is formed on the gate insulating layer132. Then, a source region and the drain region in the polysilicon layer131 are formed by an ion implantation process. Thereafter, an interlayer dielectric 134 is formed on the gate insulating layer 132 and thegate electrode 133.

Thereafter, a contact holes are formed in the gate insulating layer 132and the inter layer dielectric 134 on the source region and the drainregion. Then, a source electrode 135 b and a drain electrode 135 a,which are connected to the source region and the drain region throughthe contact holes, are formed on the inter layer dielectric 134.

Then, as the example shown in FIG. 6F, a first connection wiring 140 afor electrically connecting the drain electrode 135 a of the transistorelement 130 and the p-type semiconductor layer 123 of the micro LED 120is formed and a second connection wiring 140 b for electricallyconnecting the n-type semiconductor layer 121 of the micro LED 120 to anexternal voltage source to source line VSS is formed. The firstconnection wiring 140 a and the second connection wiring 140 b may beformed after mounting the micro LED display panel on the display devicesubstrate. In addition, as the example shown in FIG. 5, the firstconnection wiring 140 a and the second connection wiring 140 b may besequentially formed, and as the example shown in FIG. 7, the firstconnection wiring 140 a and the second connection wiring 140 b may beformed at the same time.

In the example shown in FIG. 6F, the first connection wiring 140 a canbe formed by forming a first protection layer 150 a on the substrate 110on which the micro LEDs 120 and the transistor elements 130 for drivingthe micro LEDs 120 are arranged, forming a contact hole, and depositinga metal. The first protection layer 150 a may be formed with one or morefirst contact holes 152 and 154. The first connection wiring 140 a mayelectrically connect the micro LED 120 to the transistor element 130through the first contact holes 152 and 154. In addition, the secondconnection wiring can be formed by forming a second protection layer 150b on the first protection layer 150 a formed with the first connectionwiring 140 a, forming a contact hole, and depositing a metal. The firstprotection layer 150 a and the second protection layer 150 b may beformed with one or more second contact holes 156, and the secondconnection wiring 140 b may electrically connect the micro LED 120 tothe voltage source to source line VSS through the one or more secondcontact holes 156.

Then, as the example shown in FIG. 6G, a color adjustment layer 160 canbe arranged on the light emitting region under the substrate 110. Thecolor adjustment layer 160 may include at least one of the colorconversion film and the color filter. The color conversion material suchas a fluorescent material or a quantum dot can be included in the colorconversion film.

In addition, as the example shown in FIG. 6G, a bank layer 165 can befurther arranged in the region except the light emitting region underthe substrate 110 for preventing a light leakage.

In the manner as the examples shown in FIGS. 6A to 6G, by forming themicro LED 120 and the transistor element 130 for driving the micro LEDon the same plane on the substrate 110, the micro LED display panel canbe manufactured without a transferring process of the chip in which themicro LED is formed.

While the embodiments of the present invention have been mainlydescribed hereinabove, various modifications or variations can be madein a level of those skilled in the person. Therefore, it is to beunderstood that it is included in the scope of the present inventionunless such modifications and variations deviate the scope of thepresent invention.

What is claimed is:
 1. A micro light emitting diode (LED) display panel,comprising: a substrate having a light emitting region and a drivingregion; a micro LED arranged in the light emitting region on thesubstrate; a transistor element which is arranged in the driving regionon the substrate and drives the micro LED; a first protection layercovering the micro LED and the transistor element, the first protectionlayer including one or more first contact holes; and a first connectionwiring electrically connecting the micro LED to the transistor elementthrough the one or more first contact holes in the first protectionlayer, wherein the transistor element is a polysilicon thin filmtransistor element having a polysilicon active layer, wherein at least apart of the micro LED and the polysilicon active layer of the transistorelement contact the substrate.
 2. The micro LED display panel of claim1, wherein the micro LED and the transistor element are horizontallyadjacent to each other on the substrate.
 3. The micro LED display panelof claim 2, wherein the polysilicon active layer does not overlap withthe micro LED in a vertical direction.
 4. The micro LED display panel ofclaim 1, wherein the substrate is a sapphire substrate, wherein themicro LED is a nitride based micro LED.
 5. The micro LED display panelof claim 1, wherein the micro LED includes a p-type semiconductor layer,wherein the transistor element includes a drain electrode, and whereinthe first connection wiring electrically connects the p-typesemiconductor layer of the micro LED to the drain electrode of thetransistor element through the one or more first contact holes.
 6. Themicro LED display panel of claim 1, wherein the first protection layerfurther includes a second contact hole, and wherein the micro LEDdisplay panel further comprises: a source line extending in a firstdirection; and a second connection wiring electrically connecting themicro LED to the source line through the second contact hole.
 7. Themicro LED display panel of claim 6, wherein the micro LED includes an-type semiconductor layer, and wherein the second connection wiringelectrically connects the n-type semiconductor layer of the micro LED tothe source line through the second contact hole.
 8. The micro LEDdisplay panel of claim 7, wherein the micro LED further includes ap-type semiconductor layer on the n-type semiconductor layer, at least apart of the n-type semiconductor layer horizontally extending beyond thep-type semiconductor layer, and wherein the second connection wiringcontacts the part of the n-type semiconductor layer.
 9. The micro LEDdisplay panel of claim 6, wherein the source line is arranged on thesubstrate.
 10. The micro LED display panel of claim 6, wherein the microLED display panel is mounted on another substrate, and wherein thesource line is disposed on the another substrate.
 11. The micro LEDdisplay panel of claim 6, further comprising a second protection layerdisposed on the first protection layer and the first connection wiring,and wherein the second connection wiring is disposed on the secondprotection layer.
 12. The micro LED display panel of claim 6, whereinthe first connection wiring and the second connection wiring contact thefirst protection layer.
 13. The micro LED display panel of claim 1,further comprising a color adjustment layer in a light emitting regionunder the substrate.
 14. The micro LED display panel of claim 1, furthercomprising a bank layer arranged in a region excluding the lightemitting region under the substrate.
 15. The micro LED display panel ofclaim 5, further comprising a conductive layer on the p-typesemiconductor layer for current disperse of the p-type semiconductorlayer.
 16. A micro light emitting diode (LED) display panel, comprising:a substrate having a light emitting region and a driving region; a microLED arranged in the light emitting region on the substrate; a transistorelement that is arranged in the driving region on the substrate anddrives the micro LED, the transistor element horizontally adjacent tothe micro LED on the substrate; a protection layer covering the microLED and the transistor element; and a first connection wiringelectrically connecting the micro LED to the transistor element, whereinthe transistor element is a polysilicon thin film transistor elementhaving a polysilicon active layer, wherein at least a part of the microLED and the polysilicon active layer of the transistor element contactthe substrate.
 17. The micro LED display panel of claim 16, wherein thepolysilicon active layer does not overlap with the micro LED in avertical direction.
 18. The micro LED display panel of claim 16, whereinthe protection layer includes a first contact hole exposing a portion ofthe micro LED and a second contact hole exposing a portion of thetransistor element, and wherein the first connection wiring includes afirst part extending vertically to contact the exposed portion of themicro LED through the first contact hole, and a second part extendingvertically to contact the exposed portion of the transistor elementthrough the second contact hole to electrically connect the micro LED tothe transistor element.
 19. The micro LED display panel of claim 16,further comprising a color adjustment layer in a light emitting regionunder the substrate.
 20. The micro LED display panel of claim 15,wherein the conductive layer is made of a metal.